Tower



F. M. BOWMAN TOWER Filed August :51 1925 2 Sheets-Sheet 1 May 11 ,1926F. M. BOWMAN TOWER Filed August 31. 1923 2 Sheets-Sheet 2 INVENTORPatented May 11, 1926.

UNITED STATES PATENT oFFicE.

. FRANKLIN M. BOWMAN, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 BLAW-KNOXCOMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

TOWER.

Application filed August 31, 1923. Serial No. 660,310.

The present invention relates to towers, such as are employed inengineering work for carrying transmission lines, and for signal andwireless work, and to poles, masts and similar structure, the termtowers being employed herein broadly to designate structures of thisgeneral character. I

A tower, as ordinarily constructed, has four sides, the load beingcarried principally by members at the four corners of the towerextending longitudinally thereof from the top to the bottom of thetower. The four sides of such a tower are all alike, and each isstiffened by diagonal bracing.

An object of the present invention is to provide a tower which requiresfewer structural elements than the above type of tower, while having thenecessary strength to withstand the stresses to which it may besubjected in use.

In the usual four sided tower construc- 3 tion, it is customary'to carrythe four coranchorage. A further object of the present invention is toprovide a tower having the foundation portion thereof so constructed asto effect a saving in the amount of excavation and in the amount ofconcrete required in the usual four sided tower construction.

In the accompanying drawings there is shown, for purposes ofillustration only, one embodiment of the present invention, it beingunderstood that the drawings no not define the limits of the invention,as changes may be made in the construction therein disclosed withoutdeparting from the spirit of the invention or scope of my broaderelaims.

In the drawings:

Figure 1 is a diagrammatic elevation of a tower embodying my invention;-

Figure 2 is a view of the tower taken at right angles to the view ofFigure 1;

Figures 3 and 4 are fragmentary views, corresponding to Figures land 2,of the rower portion of the tower;

Figure 5 is a horizontal sectional view taken on the line VV of Figure3, and

Figure 6 is a detail view illustrating the effect of broken transmissionwires.

Instead of having four sides and four continuous vertical corner postsat the intersection of said sides, as in the usual tower construction, atower constructed in accordance with my inventionhas only three sides.One side of the tower above the foundation is substantially the same asin the four sided tower construction, that is to say, it com prisescontinuous vertical corner posts 2 and 3 and diagonal bracing members 4.Each of the other two sides of the tower has all of its longitudinallyextending members consisting of diagonal bracing members 5, said membersbeing preferably arranged in pairs, the two members of each pairextending obliquely to and crossing each other intermediate their ends.r

The three sides of the structure are trussed at intervals by means ofhorizontal triangular frames 6 to which the ends of the members formingthe continuous posts 2 and 3 and of the diagonal bracing members i and 5are connected. The side having the diagonal bracing members 4 may alsohave horizontal truss members 7 intermediate the tri angular frames 6.These horizontal frames divide the tower structure into a number ofsuperposed stages or sections each of which is triangular in shape atits upper and lower ends. At the extreme top of the tower the horizontaltriangular frame may be omitted, thereby providing a slightly modifiedform of top stage or section of the tower in which two diagonal bracing.members 8 extend from the apex of the triangular frame 6 at the base ofthe section and are connected at their upper ends to the upper ends ofthe continuous posts 2 and 3. The frontface of this top section has twocrossing diagonals 8.

It will be apparent from the above description that one face of thetower, namely, the front face, is composed of the vertical corner posts2 and 3, diagonals 4 and 8 and horizontal members 6 and 7, while each ofthe other faces of the tower is composed of diagonals 5 and 8 andhorizontal members 6.

l Vith a tower structure as described, the wooden cross arms, such as 9,10 and 11, for carrying telephone or telegraph wires 12 and transmissionlines 13, or the like, may prieferably be arranged as illustrated inFigures 1 and 2.

The ordinary stresses applied to a tower of this character are due tothe pressure of the wind and to tension in the wires. Wind pressuretends to bend the tower so as to put the continuous post 2 in tension,and the continuous post 3 in compression, or vice versa. The forces dueto tension in the wires tend to put the diagonal members 5 and 8 incompression if the wire pull is in the direction of the arrow, Figure 2,and to put them in tension if the wire pull is in the oppositedirection. If, however, a wire on one side of the tower should break onone side of a cross arm, and a wire on the other side of the towershould break on the opposite side of the cross arm, as illustrated inFigure 6, there would be a twisting moment applied to the tower, asillustrated by the arrows in said figure. A tower constructed inaccordance with my invention is especially adapted for taking care ofsuch twisting strains, as well as for taking care of the strains due tounequal tension in the wires, and to wind pressure.

In building a steel work tower of this character, degree angle membersmay be used for all of the main elements of the tower. hen such anglemembers are used, the members forming the corner posts 2 and 3 may becrimped at suitable places, as indicated in Figure 5, to receive thediagonal bracing members and the horizontal frames. Of course, it willbe understood that angles which are rolled to 60 degrees instead of 90degrees may be employed, if desired.

The foundation portion of the structure may consist of three diagonalmembers 14-, which are connected at their upper ends to the base sectionof the tower at points adjacent the three vertices of the basetriangular frame (5 by means of connecting angles 15 and 16, and havetheir lower ends converge to substantially apoint and connected to ashort channel section 17. This foundation portion of the structure willusually be embedded in concrete which will preferably extend slightlyabove the base triangular frame 6.

An important advantage of the present invention is that it provides atower which is more economical to manufacture than the four sided tower.For example, atower such as illustrated in the drawings may beconveniently constructed from lift -seven pieces, while thecorresponding four sided tower requires siXty-four pieces. The towerillustrated may be constructed to have a total weight of 1030 pounds,while the four sided tower will have a weight of 1130 pounds to securethe same strength for like conditions of strain. These are importantconsiderations, in view of the fact that transmission towers are veryfrequently erected in places that are accessible only with difficulty,so that the weight and the number of pieces that have to be conveyed areimportant factors affecting the total cost of construction of the line.

Another important advantage arising from the invention is due to theconstruction of the foundation portion of the tower. By bringing thelongitudionally extending members to a common point, and securing themat such point, it is not necessary to rely upon the concrete to securestrength for the steel structure, but it is only necessary to rely uponit to hold the pieces of the foundation structure firmly. Moreover, asalready pointed out, there is also a saving in the amount of excavationand in the amount of concrete required to anchor the structure over thatrequired to carry down the four corner posts of the usual four sidedtower construction.

1 claim:

1. In a structural metal tower having but two uprights, means connectingthe uprights, horizontally projecting structural elements at spacedintervals in the uprights, and upwardly extending and downwardlyextending diagonals connecting the outer portions of the horizontalelements with the uprights, substantially as described.

A structural metal tower having but two spaced apart interconnecteduprights forming the main skeleton of the tower, horizontally disposedelements projecting out from the main skeleton at difierent elevations,a pair of upwardly divergent diagonals connecting the outer portion ofsome of the horizontal elements with the respective upri hts, anddownwardly divergent elements connecting the outer portion of some ofthe horizontal elements with the respective uprights, substantially asdescribed.

8. A structural metal tower having but two spaced apart interconnecteduprights forming the main skeleton of the tower, horizontally disposedelements projecting out from the main skeleton at different elevations,a pair of upwardly divergent diagonals connecting the outer portion ofsome of the horizontal elements with the respective uprights, anddownwardly divergent elements connecting the outer portion of some ofthe horizontal elements with the respective uprights, said downwardlydivergent diagonals from one of the horizontal elements crossing theupwardly divergent diagonals from a lower horizontal element,substantially as described.

l. A structural metal tower having but two spaced apart interconnecteduprights forming the main skeleton of the tower, horizontally disposedelements projecting out from the main skeleton at different elevations,a pair of upwardly divergent diagonals connecting the outer portion ofsome of the horizontal elements with the respective uprights, anddownwardly divergent elements connecting the outer portion of some ofthe horizontal elements with the respective uprights, said downwardlydivergent diagonals from one of the horizontal eleinents terminating atSubstantially the plane of the horizontal element immediately below itand wherein the upwardly divergent diagonals terminate at substantiallythe plane of the horizontal element next above it, substantially asdescribed.

5. A structural metal tower including only two spaced apart uprights,means connecting the uprights, triangular horizontal frames secured tothe uprights at suitable points therealong, diagonal braces extendingupwardly from the outer ends of some of the triangular frames to each ofthe uprights, and diagonals extending downwardly on the outer ends ofsome of the triangular frames to each of the upri hts, substantially asdescribed.

6. A structural tower including only two spaced apart uprights, aplurality of triangular frames secured to the uprights at suitableintervals, the lowermost of said frames being at the lowermost ends ofthe uprights, a downwardly extending structural member secured to eachcorner of the lowermost frame, said downwardly extending structuralelements being convergent, an anchor member to which the lowermost endsof said downwardly extending structural members are connected, a diago-'nal extending from one corner of said lowermost triangular frameupwardly to each of the uprights, and diagonals connecting the othertriangular frames with the uprights, substantially as described.

In testimony whereof I have hereunto set my hand.

FRANKLIN M. BOWMAN.

